Cutter



April 1 o. M. MAISCH 1,753,935

GUTTER Filed Apiil' 20, 1927 i valves.

Patented Apr. 8, 1930 PATET OFFICE OLIVER M. MAISO'II, OF CHICAGO, ILLINOIS CU'TTER Application fi1ed. April 20,

My invention relates 130 profile cutters and more particularly provides a cool or cutter for refacing as Well as for initially forming valve seats f0r internal combustion engine The initial design of' the internal combustion engine takes into account the size 0f valve, the angle of taper 01 the Valve face and seat, the width 0f seat in engagement wit-h the valve face and the spring tension, and all .1 these factors are interrelated to secre ehe desired action.

In the process of manufacture these factors can be determined and accurately controlled. In use the engine is subject t0 wear and it is eustomary to grind the valves inco ehe seats 110 pitted and a tight fit by the usual grinding proeess is not secured. The1l it becomes necessary to reface the valve seat loy cutting the same back to solid metal.-

The usual service station att endant 01' 1e pair man has no adequfce means for controlling ehe operation so as to niake the refaced valve seat correspond to the original factory made valve seat. Neither has he adequate means for making the valve seats in tl1e same engine alike, whether like the original seat-s 01' not.

It is the aim of the present invention 130 put into the hands of the service statioi1 mechanic or repairman a 13001 loy Which the valve seat- 5 may be refaced and brought t0 the original dimensions of diameter and Width of seat and all valve seats on one engine be made uniform. I am aware that attempts have been made to provide a profile cutter which Will clo this, laut so far as I am able to ascertain no device which can satisfactorily perform this function has been produced.

Obviously, a cutter of the right profile can be produced, lout after usage of such a cutter it becomes dulled or WOII1 and must be thrown away, loecause sharpening changes the size 01 profile of the cutterl The cutter of my invention is so constructed that by a simple grinding operation it may be dressed 0r sharpened without changing its size 01 pro- 1927. Serial N0. 185,086.

file. The key to this lies in the manner 0f relieving the cutting edges.

In a cutting tool 0f this character, which is comparable to a compound reamer, the metal behind the cutting edge must be cut back to relieve the cutt-ing edge. In a straight 0011ical reamer the edge may loe sharpened by grinding aloi1gfh fiont face, i. e., the radial face. This diminishes the diameter of the cutter at any given point, but it does noc change the taper 0f tl1e reamer and, lience, it is merely necessary 1:0 advance t-l1e reamer to bring into play a portion Which has the desired diametef.

I provide in the preferred form 0f my in Venti0n a unitary integral cutter having three cutting faces to define at their intersection.

two gaug e points or circles which are the edges of the desired valve seat. Between thesie two cireleS lie the cutters for cutting the actual face 0f the Valve seat and on each side or flank lie the cutters for cutting away tl1e adjacent metal 130 define the edges of the valve seat. These flank cutters and the valve face cutter are in realitytapered reamers and, according 130 my invention, all three 0f these reamers are relieved to the same degree and upon elements Cf thesame family of parallel heli0es, i. e. upon helices having tl1e Same Pitch laut 0f various radii.

In the preferred iorm of my invention each tooth has a radial cutting face and a helical face defining the present and future valve seat cutting edges, and upon one side 0f said s'eat cutter there is the flank cutter, and 011 the other side the port reamer, both being relieved upon the same helical pitch angle.

The key to the present construction therefore resides in the generation 01 the relief surface 011 elements 0r lines which are helices. New it is to be understood that a radial face is n0t essential. The cutter might have skewed cutting edges, as for example, helical or 'spiral, but it is advantageous to have the dressing faces radial to make the matter of sharpening easier and to conform to known practices in tool dressing.

The slight axial shift of the valve seat from the use of my cutter isreadily compensated ;Eor by adjustment 013 the valve tappet 01 thrust rods.

There are certain other improvements which 1ny invention provides, such as an improved and interchangeable guide and operating rneans as Will he apparent f1om the following detailed description of a specifie e1nbodiment.

Now t0 acquaint those skilled in the art with the manner of constructing and practicing my i1wention, I shall describe in conjunct-ion with the acco1npanying drawings, a specifio embodiment of 1ny invention.

In the drawings Fig. 1 is a side elevational view 0f my improved outter and showing it applied to a valve seat;

Fig. 2 is a central longitudinal section through the eutter;

Fig. 3 is an underside view of the cutter, a sharpening wheel being shown applied thereto;

Figs. 4 and 5 a1e enlarged diagram1natic views showing respectively a valve seat before and aftei a refacing operation with my i1nproved tool;

Fig'. 6 is a diagra1n exglaining tl1e relief, and Fig 7 is a side view of the lower end of the operating wrench 01" handle.

The cutter is preferably, laut not necessarily, formed fro1n a single piece of suitably hardened steel, and comprises the eylindrical head section 10, which may be termed the flank cutter, the frustoconical seotion 11 of lese dian1eter than that of the head, which 1nay be tenned the port realner, and tl1e intermediate vahe seat engaging belt 01 zone 12. The head, skirt and intennediate parts are 1nilled to fo11n the grooves 13 and the cut ting tooth seg1nents 14. The 1nilled grooves are shown of triangular cross section, one side 0f eaCh g1oove forming tl1e advance or autting face of a tooth and die othe1 side forming the Iear face 0f the adjacent tooth. In the specifi'o cutter here shown the cutting edge of eaeh tooth lies in a plane passing through the a:-:is of the cucter and the cutting face of each tooth preferably also lies in the sa1ne axial plane in which the cutting edge is located. In other words, the advance o1 autting face of each tooth in this instance lies in a radial plane so that ehe cutting edge of the tooth throughout its extent Will be in a radial plane ab all tirnes.

The teeth are given tl1e necessary relief or drop rearwardly of their cutting edges, and this can' loe readily accomplished by means of a ca1n fed tool operating on the rotating entter in a known fonn of 1naohine known as a relieving 1nachine. This, however, 1nust he done in a certain n1anner to securethe full benelits of the present invention.

011 1nost 0f the auton1otive vehicle engines the valve seat is at an angle of forty-five degrees with the valve opening axis and in the valve structu1e illustrated the seat is about one-sixteenth of an inch in width. When the engine is new, and before the valve seats have been refaced, the upper edges of the seats a1e coincident with the top surface S of the xnetal in which the seats a1e cut, and in the partieular structure shown there is a belt o1 surface T sunounding the valve passageway below the valve seat and which is at an angle of lese than forty-five degrees with the valve axis. This is a connnon or standard arrange1nent found in 1nost types of auto1nolive vehicles and the cutter shown has been designed to be used in such types of valve structu1es; The intermediate zone 01 belt 12, at the tooth eutting edges, is of the sa1ne width as t-l1e desi1ed width of valve seat 15 and the eutting edges at the skirt part 11 of the cutter have the same angle relative to the valve axis as the surface T. In the better dass of engines the valve ports a1e 1na(:hined concentric With die guide for the valve Stern and he valve seat 15. This machinecl suriace n1ay be cylindrical 01 tapered. In either case it provides a suitable guide for the reanier portion 11 to hold ehe tool in proper axial align1nent. The cutting edges 0'f the teeth on the umlerside of the flange 01 head part 10 constituting the flank eutter are at an angle Willi the valve axis of greater than forty-five degrees.

As shown in Fig. 3, the inner and outer edges a and Z) of the intennediate 01 valve seat engaging belt 12 will, when axially projected, lie in eoncentrie circles centered at the outter axis, the purpose o1 which Will be explained a little later.

T he cutter, in the particular arrangernent shown, has the axially extending tapered passageway o1 bore 17 whose larger end is at the top. A tapered driving spindle 18 is adapted to he inserted in the bore 17 ior frictionally driving the cutter. The spindle has at its lower end a ste1n 19 adapted to extend into o1 through the guide for the valve ste1n. The upper end of the spindle is 1nade hemispheriaal, as indicated ab 20 and is provided with radial projeccions 21.

VVhen ehe cutt-er is so be used, the driving spindle is applied thereto und the resulting tool engag'ed with the valve seat to be refaced. the ste1n 18 extending into ehe guide boss 22 in Whieh the sie1n of the removed Val\e ope1ated. The cuttei Will thus be hold in axial align1nent luring the refacing operation. The tool can be turned by hand 01 otherwise. I have shown a simple device for operating the cool, namely a socket wrench in which the socket 23 is somewhat largel' in dia1neter than fhe uppe1 end of the driving spindle. The botto1n wall of the socket is preferahly conical as indioated at 24. The wreneh i.s provided witl1 bayonet slots disposed to receive the projections 21 on the splndle. \Vhen tne wrench is applied to the spindle it 1nay rock thereon without pro ducing any side thrust, and consequently it is unnecessary for the worlnnan to exercise extreme care tol1old the vvrench accurately in alignrnent with the spindle.

As the tool is rocated the metal surrounding the valve passageway Will l0e cut by the cutting edges of the teeth. As the metal is cut away, the cutter will move downward axially and the valve seat Will shift downwardly axially and hold definitely to its predetermined angle, width and diameter. Likewise, the surface T Will shift axially downwardly and the flank cutting edges un derneath the head 10 Will cut the material above the valve seat t0 leave the surface U, Whose angle with the valve axis Will be greater than forty-five degrees in such condition as to give proper clearance. Fig. 4 shows tl1e valve seat before the refacing operation somewhat widened l0y use and valve grinding, and Fig. 5 shows ehe condition after the refacing operation, the distance Y representing the distance cf axial shift downwardly of the valve seat from its original factory made position. VVhen the valve is now reapplied, it Will have the same contact area with the valve seat as in its original factory 1nade condition, the surfaces T and U deflecting away from the valve face to leave only the valve seat for engagement with the valve. The operation cf the valve and the fi0W through the valve passageway Will therefore n0t be appreciably interfered with as a result 0f tl1e refacing operation.

After a cutter has been used for a time, itneeds to be resharpened and such resharpening must not disturb the sl1a-pe or profile 0f the cutting edges cf the teeth, otherwise tl1e cutting dimensions would be changed. The cutters are sharpened by grinding the radial planes-or cutting faces of the teeth, and as a result of such grinding the profile of the teeth 0r their cutting edges Will be shifted upwardly axially a distance, depending upon the amount of the grinding, because the linear elements of the surfaces of said cutters are l1elices, and the angularity or profile of the cutting edges relative to the cutter axis Will not be changed, nor Will the diameters 0f the imaginary cylindrical surfaces receiving the upper and lower edges of the belt 12 be changed. The di1nensions 0f tl1e cutter, so far as the refacing operation thereof is concerned, Will not be altered in the least.

I have shown a dished grinding Wheel 26 of a type commonly used f0r grinding and resharpening reamers and like cutters. The wheel is mounted on a driving spindle 27 and is preferably of disl1 shape in order to present the annular grinding surface 28 which is in a plane at right angles 130 the grinding wheel axis and of a Width sufiicient 130 span the tooth surfaces t0 be ground. During ward the axis.

grinding 01 a tooth the grinding surface 0f the grinding wheel is kept in the radial plane of the tooth cutting edge.

In Fig. 6 I l1ave shown diagraxnmatically the theoryn]pon which the tool is constructed. Consider the blank as having only a single tooth, ehe radial face 0f which lies 011 the vertical plane 2929 which plane passes through the axis, the original body 0f tl1e cutter has tl1e upper cylindrical portion 10, and the three conical surfaces 303132 are divided elf by the lines 33 and 34.

N0W assume that two cuts are made to defin'e the single cutter tooth under consideration as sl1owninheavy outline.

Next, the relieving operation is performed loy cutting back tl1e metal fro1n the edge to- Instead of the point cf the cutting cool moving in lines lying in planes parallel to the planes cf lines 33, 34, it moves in lines which are helices 0f the same pitch, but of suitably varying diameter to conform to tl1e conical nature of the body of the cutter.

As a result the lines 33, 34 which were circles disappear and they are replaced loy the helices 33 and 34 which, ab the edge 2929coincide witl1 the lines 33, 34. The teeth n1ay therefore be said to be relieved in such a manner that the faces extending rearwardly from the -cutting edges constitute bands each of Which is of uniform width throughout itslength and forms a helical surface concentric with the axis of rotation of t he cutter.

In like manner circular line 35 is obliterateel and the helical line 35 takes its place.

The same thing is true ab the lower end with respect t0 line 36 which, however, becomes merged with the relief surface of' the tapered part 32 0f the tool.

Obviously the relieving t00l, instead 0f having only a cutting point and tracing a line, 1nay comprise an edge and generate the tapered helicoidal surfaces desired.

The resulting tooth may be accurately described as having three adjacent oblique helicoidal surfaces of different obliquity.

While I have shown the cutting edge as disposed in a plane passing through the axis and the grinding operation as merely swinging this plane about the axis, it will be apparent that the cutting edge may loe a belicoid as in the case 0f the so-called spiral reamer. Obviously, instead of a cutting edge in three sections, more 0r less sections at Varying angles may be e1nployed.

If desired, the lower end 0f the stem 19 1nay have therein teeth 4:0 that Will act t0 clean out the bore in the guide 16 as the stem is pushed through the same.

I do noo intend to be limited to the details shown and described.

I claim:

A toothed cutter for refacing valve seats,

the face containing the cutting edges 0f each tooth lying in a radial plane relative to the axis 0f rotation of ehe cutter, eacl1 tootl1 being uniformly 1elievecl rearwarclly of its cutting cdges to procluce faces each of which ls uniform in widtl1 tl1roughout lts length and forms a helical band concentric witl1 tl1e axis 0f rotation 0f tl1e cutter, euch tooth 00111- prising an upper part ancl a seut-engaging part, the cutting ecl e 0f the seat-engaging part being ab an angle ancl of a wiclth C01- responding with the angularity ancl width of the seat t0 be refaced, and the cutting edge of tl1e upper part being inclined to the axis of rotation of the cutter at an angle greater than that 0f the cutting edge of the seat-e1r gaging part.

In testimony whereof, I sign this specification.

OLIVER M. MAISCH. 

